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Aim is To Compare The Rate Of Fermentation Of Given Samples Of Wheat Flour, Gram Flour, Rice Flour And Potato Juice.

Wheat flour,gram flour,rice flour and potatoes contains starch as the major constituent. Starch present in these food materials is first brought into the presence of enzyme diastase,starch undergo fermentation to give maltose.

Starch gives blue-violet colour with iodine whereas product of fermentation starch do not give any characteristic colour. When the fermentation is complete the reaction mixture stops giving blue-violet colour with iodine solution. By comparing the time required for completion of fermentation of equal amounts of different substances containing starch the rates of fermentation can be compared. The enzyme diastase is obtained by germination of moist barley seeds in dark at 15 degree celsius.When the germination is complete the temperature is raised to 60 degree celsius to stop further growth.The seeds are crushed into water and filtered.The filtrate contains enzyme diastase and is called malt extract.

Materials Required:

# Conical flask
# Test tube
# Funnel
# Filter paper
# Water bath
# 1 % Iodine solution
# Yeast
# Wheat flour
# Gram flour
# Rice flour
# Potato
# Aqueuos NaCl solution


-Take 5 gms of wheat flour in 100 ml conical flaskand add 30 ml of distilled water.

-Boil the contents of the flask for about 5 minutes.

-Filter the above contents after cooloing, the filtrate obtained is wheat flour extract.

-To the wheat flour extract. taken in a conical flask. Add 5 ml of 1% aq. NaCl solution.

-Keep this flask in a water bath maintained at a temperature of 50-60 degree celsius.Add 2 ml of malt extract.

-After 2 minutes take 2 drops of the reaction mixture and add to diluted iodine solution.

-Repeat step 6 after every 2 minutes.When no bluish colour is produced the fermentation is completed.

-Record the total time taken for completion of fermentation.

-Repeat the experiment with gram flour extract,rice,flour extract, potato extract and record the observations.

Observation Table

Time required for the fermentation----

Wheat flour -- 10 hours
Gram flour -- 12.5 hours
Rice flour -- 15 hours
Potato -- 13 hours


• Rice flour takes maximum time for fermentation and wheat flour takes the minimum time for fermentation.